JERUSALEM (AP) — Israel and Hamas have agreed to a 72-hour humanitarian cease-fire to begin Friday morning, the United Nations and United States announced, although Secretary of State John Kerry cautioned there were "no guarantees" the lull in violence would bring an end to the 24-day-old Gaza war.

The surprise announcement came hours after Israeli Prime Minister Benjamin Netanyahu vowed to destroy Hamas' tunnel network "with or without a cease-fire" and as the Palestinian death toll soared past 1,400.

Noting the difficulties that lay ahead, Kerry said: "This is not a time for congratulations or joy or anything except a serious determination — a focus by everybody to try to figure out the road ahead."

At least four short humanitarian cease-fires have been announced since the conflict began, but each has been broken within a few hours by renewed fighting.

A joint statement released simultaneously by Kerry and at U.N. headquarters in New York said the U.S. and U.N. had gotten assurances that all parties to the conflict had agreed to an unconditional cease-fire, and would send delegations to Cairo for negotiations aimed at reaching a lasting truce.

Soon after, an official at the prime minister's office confirmed that Israel had agreed to a 72-hour truce beginning at 8 a.m. local time Friday. Hamas spokesman Sami Abu Zuhri said the Islamic militant group also had signed on, "as long as the other party is in agreement to it."

Israeli and Palestinian delegations were expected to travel immediately to Cairo for talks with the Egyptian government aimed at reaching an end to the conflict.

"It is up to the parties — all of them — to take advantage of this moment," Kerry said. "There are no guarantees. This is a difficult, complicated issue."

During the cease-fire, Kerry said Israel will be able to continue its defense operations to destroy tunnels that are behind its territorial lines. The Palestinians will be able to receive food, medicine and humanitarian assistance, bury their dead, treat the wounded and travel to their homes. The time also will be used to make repairs to water and energy systems.

"We hope this moment can be grabbed by both parties, but no one can force them to do that," Kerry said.

"Israel has to live without terror and tunnels and rockets and sirens going on through the day," he said. "Palestinians have to be able to live freely and share in the rest of the world and live a life that is different from the one they have long suffered."

The Palestinian delegation is expected to include members of Hamas, which the United States and Israel consider a terrorist organization and cannot be negotiated with directly. So if the Israelis and Palestinians meet face to face, the Hamas members will not participate in those talks.

The Egyptians will be the go-between for the sides and will help coordinate, a senior State Department official said, speaking on condition of anonymity because the official wasn't allowed to discuss the issue publicly.

U.N. spokesman Stephane Dujarric said the cease-fire was the result of Secretary-General Ban Ki-moon's recent trip to the region "but also 48 hours of extremely active diplomacy at all levels from the secretary-general to his senior advisers talking to key regional players."

Robert Serry, the U.N. special coordinator for the Middle East peace process, U.S. Mideast envoy Frank Lowenstein and others were expected to go to Cairo for the Egyptian-mediated talks.

At least 1,441 Palestinians have been killed, three-quarters of them civilians, since hostilities began on July 8, according to Gaza health ministry officials — surpassing the at least 1,410 Palestinians killed in Israel's last major invasion in 2009, according to Palestinian rights groups.

Israel says 56 soldiers, two Israeli civilians and a Thai agricultural worker also have died — far more than the 13 Israeli deaths in the previous campaign.

Israel expanded what started as an aerial campaign against Hamas and widened it into a ground offensive on July 17. Since then, Israel says the campaign has concentrated on destroying cross-border tunnels militants constructed to carry out attacks inside Israeli territory and ending rocket attacks on its cities.

For its part, Hamas has said it will only halt fire once it receives guarantees that a Gaza border blockade by Israel and Egypt — tightened after the Islamic militant group violently seized power in Gaza in 2007 — will be lifted.

Israel says most of the 32 tunnels it has uncovered have now been demolished. But Netanyahu said Thursday he would reject any proposal that prevents the Israeli military from completing the destruction of Hamas' tunnel network.

"We have neutralized dozens of terror tunnels and we are committed to complete this mission, with or without a cease-fire," Netanyahu said in televised remarks. "Therefore, I will not agree to any offer that does not allow the military to complete this important mission for the security of the people of Israel."

For Israel, the tunnel network is a strategic threat. It says the tunnels are meant to facilitate mass attacks on civilians and soldiers inside Israel, as well as kidnappings, a tactic that Hamas has used in the past. Palestinian militants trying to sneak into Israel through the tunnels have been found with sedatives and handcuffs, an indication they were planning abductions, the military says.

Several soldiers have been killed in the current round of fighting by Palestinian gunmen who popped out of underground tunnels near Israeli communities along the Gaza border.

Earlier Thursday, the Israeli military announced it was calling up an additional 16,000 reserve soldiers to pursue its campaign against the Islamic militants. Israeli defense officials said the purpose of the latest call-up was to provide relief for troops currently on the Gaza firing line, and amounted to a rotation that left the overall number of mobilized reservists at around 70,000. They spoke on condition of anonymity in line with regulations.

However, Israeli officials have also said they do not rule out broadening operations in the coming days.

Palestinians have fired more than 2,850 rockets at Israel — some reaching major cities but most intercepted by the Iron Dome defense system. On Thursday alone, more than 100 rockets were fired toward Israeli cities, the army said.

Israel has launched more than 4,000 strikes against Hamas-linked targets, including rocket launchers and mosques where it says weapons were being stored.

One Israeli was seriously wounded when a rocket exploded in a residential area of Kiryat Gat in southern Israel, the military said. The rocket damaged a house and destroyed several cars parked on the street. Another rocket was intercepted over Tel Aviv by Israel's rocket defense system, the army said.

Gazans said munitions struck the Omar Ibn al-Khatab mosque next to a U.N. school in the northern town of Beit Lahiya. The office of the military spokesman said Palestinian snipers inside the mosque had shot at troops, wounding one Israeli soldier and prompting retaliatory fire.

The strike in Beit Lahiya damaged water tanks on the roof of a building near the mosque, sending shrapnel flying into the adjacent school compound, where dozens of Palestinians displaced by the fighting had taken shelter.

"The shrapnel from the strike on the mosque hit people who were in the street and at the entrance of the school," said Sami Salebi, an area resident.

Gaza health official Ashraf al-Kidra said at least 15 people were wounded in the strike, including three who were in critical condition.

Among them was Kifah Rafati, who was being treated for shrapnel injuries at the nearby Kamal Adwan Hospital. She said she and her six children had been sleeping in a classroom inside the U.N. school when the explosion went off.